Method and safety device for the remote-control of self-propelling working machines

ABSTRACT

A soil compacting machine has a receiver unit that can receive control signals from a transmitter unit to a receiver unit. The transmitter unit can be operated by a user and is separate from the machine. The control signals are then processed into commands and sent to a control mechanism of the machine. Signals originating from the transmitter unit and reflected by the machine are received as safety signals by a receiver connected to the transmitter unit and are tested in relation to at least one distance-dependent parameter. If the parameter which is tested shows that a predetermined safety distance between the machine and the receiver is not respected, the transmission of the control signals or the operation of the machine is interrupted.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention concerns a method according to the preamble of claim 1 anda safety device according to the preamble of claim 9.

2. Description of the Related Art

There is a known method for the remote control of self-propellingworking machines, especially soil-compacting machines such as rollers,vibration plates or the like, in which control signals are sent by meansof a transmitting unit, which can be operated by an operator and areseparate from the working machine, to a receiving unit on the workingmachine and are processed by the receiving unit for generating anelectrical control signal for controlling the working machine.

In the remote control of self-propelling working machines it must beensured that an adequate safety distance is maintained between theoperator and the working machine to rule out any danger to the operatorfrom the running working machine. In the case of trench rollers thereare legal regulations prescribing a minimum distance between the trenchroller and the operator. If the distance is not respected, allpotentially dangerous movements must be prevented, so that the trenchroller must be immediately stopped.

DE 42 21 793 C1 discloses an infrared remote control for self-propellingsoil-compacting machines which sends from a control device carried bythe operator not only the infrared control radiation intended for thefunctional control of the working machine but also infrared near-rangeradiation at much lower intensity than the control radiation, so thatthis near-range radiation can be received with adequate intensity onlyin close proximity to the transmitter. When this near-range radiation isreceived, the generation of electric signals, which are caused by thecontrol radiation and otherwise make the working machine move along, issuppressed in the receiving unit on the working machine.

Using this method, the working machine can be moved as long as a safetysignal does not arrive with adequate intensity at the working machine.Attenuations of the signal intensity that are not based on a largedistance between the transmitter and receiver required for safetyreasons may lead to the working machine still being able to move even ifthe safety distance is no longer being respected. Such a source of errorresults from the fact that the receiving eye, for example on a trenchroller, is usually not arranged centrally, with respect to the directionof propulsion, but at the intended place for the operator in the regionof one of the end faces. This produces an unsymmetrical receiving fieldwith respect to the trench roller, with the effect that, when theoperator with the transmitter is in front of the end face of the machineaway from the receiving eye, the actual safety distance between theoperator and the machine is shortened by the distance which existsbetween this end face and the receiving eye, that is for example by 2 min comparison with the safety distance when the operator is in front ofthe other end face of the machine. If the operator stands very close tothe end face of the machine away from the receiving eye, this effect isintensified even further by the fact that the assumed 2 m of machinelength that have to be bridged between the transmitter and the receivingeye can shield the radiation. While the weak safety signals cannot reachthe receiving eye for the reasons mentioned, the strong control signals,which may be reflected by lateral trench walls, arrive at the receivingeye and, as a result, give the impression that there is an adequatesafety distance.

If the receiving eye for the safety signal is located on the workingmachine, there is a tendency for it to become soiled, which may causesignal attenuation. This may also have the effect of giving the falseimpression of an adequate safety distance, even if the predeterminedsafety distance is no longer being respected.

DE 196 00 791 A1 discloses a remote control in which the distance of theremote control devices from a working machine is concluded from thesignals sent by evaluating the phase or intensity of the signals, inorder to avoid the overlapping of effective ranges of different remotecontrols. The purpose of this arrangement is to limit as accurately aspossible the range of each radio control transmitter to a fixed workingrange, in order to avoid any danger to personnel in the working andeffective range of the radio-remote-controlled equipment.

OBJECTS AND SUMMARY OF THE INVENTION

The invention is based on the object of designing the method stated atthe beginning in such a way that a more reliable safety signal isavailable. The invention is also based on the object of specifying asuitable safety device.

The solution achieving the object according to the defining part ofclaim 1 is that signals coming from the transmitting unit and reflectedby the working machine are picked up as safety signals by a receiverconnected to the transmitting unit, at least one distance-dependentparameter of the safety signals picked up by the receiver is checked andthe operation of the working machine is interrupted if the checkedparameter indicates that a predetermined safety distance between theworking machine and the receiver is not being respected.

Since in the case of the method according to the invention the distanceis measured between the transmitting and receiving unit for the safetysignal, carried by the operator, and the side of the working machineimmediately opposite the transmitter and reflecting the safety signal,the source of errors caused by an unsymmetrical arrangement of thereceiving eye on the working machine is eliminated. Since no signalprocessing but only a reflection takes place on the working machine withrespect to the safety signal, the risk of signal attenuation due to asoiled receiving eye is greatly reduced, because on the one hand therisk of soiling is much less for the receiving eye remote from theworking machine on the transmitting unit and on the other hand it ispossible for this receiving eye to be cleaned at any time without havingto relinquish the safety distance between the operator and the workingmachine.

The operation of the working machine is advantageously interrupted bysending a stop signal from the transmitting unit or by interrupting thesending of the control signals.

A simple embodiment consists in that the control signals reflected bythe working machine are checked by the receiver connected to thetransmitting unit. In the case of a preferred refinement, safety signalsseparate from the control signals are sent by the transmitting deviceand, after reflection at the working machine, are checked by thereceiver connected to the transmitting unit. In this case, the safetysignals can be sent as electromagnetic radiation or else be transmittedin the infrared frequency range, it then being possible to check theintensity of the safety signals to establish that the safety distance isbeing maintained. However, the safety signals may also be sent asacoustic signals in the ultrasonic range, the transit time of the safetysignals between the transmitter and receiver being checked at thetransmitting unit.

The invention also relates to a safety device for remote-controlled,self-propelling working machines for carrying out the method accordingto the invention with a control device which is to be carried by anoperator and comprises a transmitter for sending control signals to areceiver arranged on the working machine and connected to the control ofthe latter, it being provided according to the invention that thecontrol device is connected to a receiver for signals coming from thecontrol device and reflected by the working machine, to which devicethere is assigned a testing circuit for checking at least one parameterof the received, reflected signals that is dependent on the distancebetween the reflecting surface of the working machine and the receiver,which circuit is suitable for interrupting the operation of the workingmachine if a predetermined test condition occurs. For interrupting theoperation of the working machine, the sending of the control signals canbe interrupted or a stop signal can be sent.

In this case, the control device preferably comprises not only atransmitter for control signals but also a transmitter for safetysignals, and the receiver of the control device is tuned to the safetysignals.

In this case, the transmitter for safety signals may be an infraredtransmitter or else an ultrasonic transmitter.

BRIEF DESCRIPTION OF THE DRAWING

The invention is explained in more detail on the basis of thedescription now following of an exemplary embodiment thereof,represented in the single FIGURE.

The FIGURE shows in a schematic plan view a working machine in the formof a trench roller and an assigned infrared hand-held transmitter as thecontrol device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

At one end of a self-propelling trench roller 10, which can beremote-controlled by means of infrared beams, there is a receiving eye12 for the infrared control beams 14, which emerge in a directed mannerfrom a transmitting eye 16 of a portable control device 18, which iscarried by an operator. Control commands entered in the control deviceby the operator are transmitted to a controller of the trench roller 10by means of these control beams 14.

The arriving radiation is reflected by the outside wall of the trenchroller 10, as is shown by the example of the transmission beam 14 a andthe reflected beam 14 b. As a result, the reflected radiation passes toa reflex receiver 20, provided on the control device 18. The beamsarriving at this reflex receiver 20 are checked by a testing circuit(not shown), accommodated in the control device 18, in order toestablish on the basis of at least one preselected parameter and a limitvalue assigned to it whether the control device is inside or outside asafety zone surrounding the trench roller. If the limit value isexceeded, the trench roller is stopped, which can take place for exampleby preventing the sending of control commands or by sending a stopsignal.

The reflex receiver 20 may be tuned to the control signals coming fromthe transmitting eye 16. However, separate safety signals may also besent in the infrared range, to which the reflex receiver 20 is tuned. Inthis case, commercially available so-called “light scanners” may beused. It is consequently possible, for example, to use an RF radiationfor the transmission of the control commands.

In the case of infrared safety signals, the intensity of the reflectedinfrared radiation may be evaluated as a parameter for the distancebetween the control device and the trench roller. However, ultrasonicsignals may also be sent as safety signals, it then being possible forthe transit time of the signals to be used as a parameter.

What is claimed is:
 1. A method for the remote control of aself-propelling soil-compacting machine, comprising: sending controlsignals via a transmitting unit, which can be operated by an operatorand which is separate from the machine, to a receiving unit on themachine; processing the control signals received by the receiving unitto form control commands to be issued to a controller of the machine,wherein signals coming from the transmitting unit and reflected by themachine are picked up as safety signals by a receiver connected to thetransmitting unit; checking at least one distance-dependent parameter ofthe safety signals picked up by the receiver; and interrupting theoperation of the machine if the checked parameter indicates that apredetermined safety distance between the machine and the receiver isnot being respected.
 2. The method as claimed in claim 1, wherein theoperation of the machine is interrupted by sending a stop signal fromthe transmitting unit or by interrupting the sending of the controlsignals.
 3. The method as claimed in claim 1, wherein the controlsignals reflected by the machine are checked by the receiver.
 4. Themethod as claimed in claim 1, wherein safety signals separate from thecontrol signals are sent by the transmitting unit and, after reflectionat the machine, are checked by the receiver.
 5. The method as claimed inclaim 4, wherein the safety signals are sent as electromagneticradiation or in the infrared frequency range.
 6. The method as claimedin claim 5, wherein the intensity of the safety signals is checked. 7.The method as claimed in claim 4, wherein the safety signals are sent asacoustic signals in the ultrasonic range.
 8. The method as claimed inclaim 7, wherein the transit time of the safety signals is checked.
 9. Asafety device for a remote-controlled, self-propelling working machinefor carrying out the method as claimed in claim 1, said safety devicecomprising: a control device which can be carried by an operator, andwhich comprises a transmitting unit and a receiver, wherein thetransmitting unit is configured to send control signals to a receivingunit on the working machine and is connected to a controller of theworking machine, wherein the receiver is configured to receive signalscoming from the transmitting unit and reflected by the working machine,to which control device there is assigned a testing circuit for checkingat least one parameter of the received, reflected signals that isdependent on the distance between the working machine and the receiver,the testing circuit being suitable for interrupting the operation of theworking machine if a predetermined test condition occurs.
 10. The safetydevice as claimed in claim 9, wherein, for interrupting the operation ofthe working machine, the sending of the control signals can beinterrupted or a stop signal can be sent from the transmitting unit. 11.The safety device as claimed in claim 9, wherein the transmitting unithas a transmitter for control signals and a transmitter for safetysignals, and wherein the receiver assigned to the transmitting unit istuned to the safety signals.
 12. The safety device as claimed in claim11, wherein the transmitter for safety signals is an infraredtransmitter and the testing circuit is suitable for determining theintensity of the received, reflected signals.
 13. The safety device asclaimed in claim 11, wherein the transmitter for safety signals is anultrasonic transmitter and the testing circuit is suitable fordetermining the transit time of the received, reflected signals.
 14. Amethod for the remote control of self-propelling working machines,comprising: (A) sending control signals from a transmitting unit, whichcan be operated by an operator and which is separate from the workingmachine, to a receiving unit on the working machine; (B) processing thecontrol signals received by the receiving unit to form control commandsto be issued to a controller of the working machine, wherein signalscoming from the transmitting unit and reflected by the working machineare picked up as safety signals by a receiver that is connected to thetransmitting unit; and (C) checking at least one distance-dependentparameter of the safety signals picked up by the receiver; and (D)automatically interrupting the operation of the working machine if thechecked parameter indicates that a predetermined safety distance betweenthe working machine and the receiver is not being respected.
 15. Amethod as defined in claim 14, wherein the operation of the workingmachine is interrupted by sending a stop signal from the transmittingunit or by interrupting the sending of the control signals.
 16. A methodas defined in claim 14, wherein the control signals reflected by theworking machine are checked by the receiver connected to thetransmitting unit.
 17. A method as defined in claim 14, wherein safetysignals separate from the control signals are sent by the transmittingunit and, after reflection at the working machine, are checked by thereceiver connected to the transmitting unit.
 18. A method as defined inclaim 17, wherein the safety signals are sent as electromagneticradiation or in the infrared frequency range.
 19. A method as defined inclaim 18, wherein the intensity of the safety signals is checked.
 20. Amethod as defined in claim 17, wherein the safety signals are sent asacoustic signals in the ultrasonic range.
 21. A method as defined inclaim 20, wherein the transit time of the safety signals is checked. 22.A safety device for remote-controlled, self-propelling working machinescomprising: (A) a first receiver disposed on the working machine, thefirst receiver being coupled to a controller for the working machine;(B) a control device which is configured to be carried by an operator;(C) a transmitter which is located on the control device and which isconfigured to send control signals to the first receiver; and (D) asecond receiver which is located on the control device and which isconfigured to receive signals sent from the transmitter and reflected bythe working machine, wherein the control device includes a testingcircuit for checking at least one parameter of the received, reflectedsignals that is dependent on the distance between the working machineand the second receiver, the testing circuit being configured tointerrupt the operation of the working machine if a predetermined testcondition occurs.
 23. A safety device as defined in claim 22, wherein,for the interruption of the operation of the working machine, thesending of the control signals by the transmitter can be interrupted ora stop signal can be sent from the control device.
 24. A safety deviceas defined in claim 22, wherein the control device further comprises atransmitter for safety signals, and wherein the second receiver is tunedto the safety signals.
 25. A safety device as defined in claim 24,wherein the transmitter for safety signals is an infrared transmitter,and wherein the testing circuit is configured to determine the intensityof the received, reflected signals.
 26. A safety device as defined inclaim 24, wherein the transmitter for safety signals is an ultrasonictransmitter, and wherein the testing circuit is configured to determinethe transit time of the received, reflected signals.